The in vivo administration of monoclonal antibodies (mAbs) that bind to cell-surface glycoproteins can block the actions mediated by those molecules, deliver stimulatory signals through the bound molecules, or result in depletion of the targeted cell population. This approach has been extremely useful to study immunopathogenic events in rodent models. Emerging recombinant antibody technologies now can provide chimerized, humanized and primatized antibodies, making similar experimental approaches feasible in NHP models. Among NIH investigators funded through eight NIH Institutes or Centers, the applicants documented a need for access to antibodies capable of depleting subsets of lymphocytes. The generation of these recombinant antibodies as research tools can be best realized by creating a resource for identifying and developing mAbs relevant to the NHP models and for optimizing the experimental protocols for their use. Furthermore, maximizing accessibility to these unique reagents will require manufacturing and distributing large quantities of highly purified mAbs appropriate for use in NHPs. In this application the investigators propose to develop a resource that facilitates the use of mAbs as research reagents in NHPs. Specificically, the applicants will establish a resource to: 1) Identify, produce, test and distribute existing mAbs that will serve as relevant research tools in NHP models; 2) Optimize the use of these mAb research reagents and characterize the models in which they are used; 3) Develop second generation recombinant antibodies that have longer durations of action using emerging molecular techniques.